Ron Guth:
Proof 1854 Large Cents are very rare and perhaps even more rare than they are generally perceived to be. I've heard estimates of two dozen known to more than 30 but when I reviewed the Auction Prices Realized and eliminated duplicate appearances, I could find only fourteen demonstrably different examples in all color designations. Of those, the finest known is a PCGS PR66RB.
It appears that only one die pair (N-12) was used to strike Proofs, then those dies were used to create coins for circulation.